(3aS,4S,6aR)-Hexahydro-2-oxo-N-(15-oxo-3,6,9,12-tetraoxa-16-azanonadec-18-yn-1-yl)-1H-thieno[3,4-d]imidazole-4-pentanamide

This linker is designed to connect a warhead-bearing ligand to an E3-recruiting moiety in PROTAC architectures, enabling controlled spatial presentation and efficient ternary-complex formation. Its heteroatom-rich, amide-containing framework supports conformational tuning and robust chemical handling during synthesis. Researchers can leverage these structural features to build degraders with improved coupling efficiency and predictable linker integrity; detailed structural and reactivity considerations are provided below.

Structure: The linker comprises a thieno[3,4-d]imidazole core bearing a pentanamide functionality and an extended polyether/aza chain. Multiple heteroatoms (oxygen and nitrogen) provide hydrogen-bonding capacity, while the terminal alkyne enables selective coupling. Amide and heteroaromatic bonds contribute to stability and defined geometry.

Reactivity: The terminal alkyne supports alkyne-selective conjugation strategies commonly used in PROTAC synthesis, including click-type bond formation with azide partners under copper-catalyzed or catalyst-free conditions, depending on substrate compatibility. Amide formation or substitution steps typically proceed via activated carboxylic acid intermediates using standard peptide-coupling reagents. Polar aprotic solvents and inert atmospheres are often employed to maintain linker integrity and suppress side reactions.